Dry blending aid

ABSTRACT

A method of monitoring and evaluating the dry-blending of powders and granular materials via the use of non-dissolvable particulate matter such as mustard seed as a blending aid. The mustard seed is blended into the total batch of dry blend materials and the mustard send can subsequently be extracted by a process of sieving from a known volume of sample taken of the mixture since the mustard seed is larger than the other particles that are being blended. The weight and or sight count of the extracted mustard seed present in the sample is determined and compared with the amount of seed that should be present in a perfect blend to determine if the dry blend materials are thoroughly mixed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/106,545, filed Apr. 21, 2009, which claims the benefit of U.S.Provisional Patent Application No. 60/916,648, filed May 8, 2007, bothof which are specifically incorporated by reference in their entiretyherein without disclaimer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is a method that uses a dry blending aid in theform of mustard seeds to monitor and evaluate the dry-blending ofpowders and granular materials. A known proportion of mustard seed todry blending materials is added to a mixer and mixed together. Samplesare taken, the mustard seeds sieved out of the other materials andmeasured. The proportion of mustard seeds in the sample are thencompared with the expected proportion in the total mixture to determineif the dry blending materials are thoroughly mixed.

2. Description of the Related Art

Currently there is no quick and easy way of directly determining whetherdry blending mixtures such as cement are thoroughly blended. Thus theoperator must make a determination based on past experience and based onlab results from similar mixtures that were previously mixed.

For example, a sample of dry blended cement mixture is taken from themixture after a given time interval and taken to the laboratory where itis mixed with water and allowed to harden. The time required for themixture to harden is an indirect indication of whether the dry blendedcement was adequately mixed.

Obviously because of the length of time required to do this type oflaboratory work on a sample, in commercial cement mixing operation themixture upon which the sample was taken will have already been removedfrom the mixer and new batches will have been mixed. For this reason,this type of testing procedure is not adequate when a new custom blendis being made. In those situations, the blend time needed to thoroughlymix the components might be more or less than the time required forpreviously tested mixtures having different components.

The present invention addresses this problem by providing a fast andeasy way of obtaining a direct measure of the degree of mixing that hasoccurred in a dry blending mixture. This invention is based on theprincipal that if one component in the mixture is thoroughly mixed, thenall components in the mixture should also be thoroughly mixed. Thepresent invention adds mustard seed as a blending aide in the mixture tobe blended. The mustard seed is added at a known concentration to thedry blending mixture and then the mixture is mixed. A sample of themixture is then obtained and the mustard seeds separated from the otherdry mixture components. The mustard seeds are then weighed or countedand the concentration of mustard seeds in the sample is obtained andcompared with the theoretical or expected concentration that should bepresent in the mixture if the mixture is thoroughly mixed. If theconcentration of mustard seed in the sample matches the expectedconcentration, then the mixture is thoroughly mixed. Mustard seeds areinert and non-hazardous and do not affect the properties of the finishedmixture. They are therefore a good choice as an indicator of whether thecomponents of the mixture have been adequately mixed.

SUMMARY OF THE INVENTION

The present invention relates to a method of monitoring and evaluatingthe dry-blending of powders and granular materials via the use ofnon-dissolvable particulate matter, such as mustard seed, as blendingaid. The mustard seed has a unique and uniform size of between 1.5 to2.0 mm which is larger than the other particles that are being blended,has uniform density, and is inert in that it is not viable seed thatwill sprout when exposed to moisture. Also, mustard seed is not reactiveor hazardous. The mustard seed is blended into the total batch ofdry-blend materials and the mustard seed is subsequently extracted froma known sample volume of the mixture by a process of sieving. The weightand or sight count of the extracted mustard seed present in the sampleis determined and compared with the amount of seed that should bepresent in the sample in a perfect blend to determine if the dry blendmaterials are thoroughly mixed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to a method of monitoring and evaluatingthe dry-blending of powders and granular materials via the use ofnon-dissolvable particulate matter, such as mustard seed, as blendingaid. The preferred material is mustard seed that has uniform size and isnot viable seed. The mustard seed that is used is this method has beenprocessed as would be the case for food grade mustard seed. The seed hasa limited variation in size of 1.5 to 2.0 mm. Also, the food grademustard seeds are not viable and therefore do no sprout when exposed tomoisture. Mustard seed is used because it has a unique size and densityin an inert structure. This material is blended into the total batch ofdry-blend and removed by a process of sieving. Then by weight and orsight count the unique material is extracted and calculated as to amountpresent verses amount that should be present in a perfect blend.

The amount of blending aid to be added should be 1 to 2 pounds ofmustard seed per 1000 pounds of total dry blend. The materials to beblended and the mustard seed blending aid should be added to blender ina manner that is safest for personnel and is recommended by the blendermanufacturer. A small amount of the mustard seed blending aid is addeddirectly to the dry-blend materials. It is inert and density compatiblewith the materials. The blending-aid should be added last after allother materials have been added. There are no known hazards associatedwith the blending-aid.

At any time during the blending a sample of the dry-blend is extracted(usually about one pound). This can be done at approximately 5 minutesor whatever time is deemed appropriate. An initial sample of the blendshould be taken to evaluate the blending and the sample should beobtained by using a dipper that can extract an exact volume from themixer. The dipper should then be tapped repeatedly to settle contents.Sufficient excess of the blend should then be added to the dipper tooverfill the dipper and then a straight edge can be used to level offthe sample at the top of the dipper to obtain an exact and repeatablevolume.

The content of the dipper is then used as the sample. The entire sampleis dumped into a 20 mesh (0.85 mm to 0.5 mm) screen sieve and sievedthrough a screen. Although a 20 mesh screen sieve is specified, a 30mesh screen sieve might also be used, depending on the particle size ofthe other material in the sample. The retained particles left on thesieve will be the mustard seed blending aid. These particles are easilyseparated and identified by this technique. The mustard seed particlescan then be weighted and also counted if desired. Of course the materialto be dry-blended should be finer than the blending-aid so that they arenot retained on the 20 mesh screen or the 30 mesh screen if that screensize is used, with the mustard seed blending aid.

At intervals of 5 minutes or whatever time intervals are deemedappropriate, additional samples can be taken as described for theinitial sampling and then those samples can be sieved and the retainedparticles weighed and also counted if desired.

The results are evaluated and when the amount of measured dry-blendingaid found in the sample is consistent with the calculated amountexpected for a fully mixed sample of the sample's volume, the blendshould be considered homogeneously blended. Blending can be continuedfurther to check for optimum blending time.

An example of the process of the invention would be to add 1 pound ofthe blending-aid to 1000 pounds of dry material to be blended. Thiswould result in 0.1 gram of blending-aid particles in each 100 grams ofblend when a homogeneous blend has been accomplished. If in addition tothe evaluation of small admixture blending into a large blend, thedetermination of the bulk density of the final blend is important, thenthe use of a ladle or sample dipper of known volume can be used todetermine the bulk density of the final product. This is important ifthe blend mixture includes light weight, density reducing materials suchas pozzolans, glass bubbles, or other such materials commonly used incement mixtures. Bulk density is the weight/volume relationship of a drymaterial, and is a convenient way to verify accuracy of the blending oflarge amounts of varying density materials. A verified laboratory smallblend is used as the standard to compare field blending samples. Adipper of 1 pint size could be used to extract some material from theblender and the dipper tapped until the volume of the material in thedipper stabilizes. Then excess material added to the dipper to overfillit and then the excess removed with a straight edge to get and exact andrepeatable sample size.

The sample should first be weighed and then sieved through a 20 or 30mesh screen. A large 12 inch sieve that fits the top of a 5 gallonbucket is convenient for this procedure. The retained blending-aidparticles left on the screen are then weighed and counted if desired.This will give the weight volume (bulk density) of the entire sample andthe weight and count of the blending-aid particles. Since the exactamount of mustard seen blending aid added to the dry-blend is known, theperfect blend amount of mustard seen blending aid is expected to betaken from the extracted sample of dry-blend when blending is complete.If the particles of the same that are retained on the screen are at thecalculated concentration for the blend of the blending aid in the batchof materials being blended, then blending is good.

A chart can be created to make it easy for the technician to quicklydetermine if the amount of mustard seed blending aid contained in asample falls within the expected range for a fully blended mixture bythis particle tracing for blend analysis method. Once created, such achart is used to verify blending of small concentrations of additive.The particles used have been selected based on their density and size inorder to have a traceable particle by simple sieve analysis and visualparticle counting. Adding 1 pound of particles to 1000 pounds of blendwill result in 0.1 gram of particles in 100 grams of sample if correctlyblended. This is approximately 19 particles in a 100 gram sample. Aweighed sample of the blend with particles added can be sieved in alarge sized sieve of 20 to 30 mesh size. A 12 inch sieve that fits inthe top of a 5 gallon bucket is convenient. The particles are easilyseen and can be weighed or counted.

Once the mixture is considered to have been well blended, the blend canthen be used for the intended purpose since the blending aid is inertand should not interfere with the product.

Alternately, sampling can be continued as long as desired at intervalsdeemed appropriate to further evaluate the blending procedure. Since theblending-aid is non-reactive it can be added routinely to allow blendchecking as desired. The blending-aid of the patent is primarily a drymaterial blending-aid, but it would be feasible to use the blending-aidin a thick liquid or “slurry” to evaluate mixture efficiency.

Also, it would be feasible to gain information using the blending-aidmaterial of the patent by extracting the blending-aid material in anautomated process.

This method was initially designed to enable operators of dry-blendingfacilities to verify the accuracy of critical dry blends of cement andadditives which may be less than 0.1% of the total blend. The methodallows the user to evaluate the efficiency of conventional dry-blendingfacilities when dry powders such as Portland cement and add mixtures areto be blended together in critical mixtures. Also, the method can beutilized for other materials that are not easily evaluated whendry-blended together.

Although the main purpose for this method is cement dry-blending, it canbe utilized in other dry-blending operations since the mustard seeds arenon-toxic and non-hazardous. Also, as a residue, the mustard seeds areenvironmentally clean. The method does not present any environmentalproblems due to toxicity or waste control.

There are no highly technical requirements for the use of the mustardseed blending aid, and the method does not require investment inexpensive and fragile monitoring and sensing devices. The method doesnot require any sophisticated monitoring devices or reactive tracerelements that might contaminate the blend. The mustard seeds arerelatively inert in the final mixed product.

While the invention has been described as employing mustard seed, othernatural or artificial seeds or grains of similar size and density mayoptionally be employed instead of the mustard seed.

While the invention has been described with a certain degree ofparticularity, it is manifest that many changes may be made in thedetails of construction and the arrangement of components withoutdeparting from the spirit and scope of this disclosure. It is understoodthat the invention is not limited to the embodiments set forth hereinfor the purposes of exemplification, but is to be limited only by thescope of the attached claim or claims, including the full range ofequivalency to which each element thereof is entitled.

1. A dry blending aid for monitoring and evaluating the blending ofmaterials comprising: a known amount of non-dissolvable particulatematter for addition to a known amount of material to be mixed, and saidparticulate matter is not affected when exposed to moisture.
 2. A dryblending aid for monitoring and evaluating the blending of materialsaccording to claim 1 wherein the particulate matter are of a uniformsize of between 1.5 and 2.0 mm.
 3. A dry blending aid for monitoring andevaluating the blending of materials according to claim 1 wherein theparticulate matter is mustard seed.